Extraction of methyl chloride from hydrocarbons



June 1943- o. H. DAWSON ETAL EXTRACTION OF METHYL CHLORIDE FROM HYDROCARBONS Filed July 13, 1945 Friedel-Crnft Catalyst Methyl Chloride lsO-Olefi Mixing -Reactor Methyl Chloride Isa-Olefin,

lso aNormcll Olefins Normal Olefin a Diolefin Feed Chiller Separating Zone INVENTORS.

Alcohol a Methyl Chloride Wola r Polymer Wafer Alcohol Alcohol Patented June 15, 1948 EXTRACTIONOF METHYL CHLORIDE FROM HYDROCARBONS Oliver H. Dawson and Hampton G. Cornell, Baytown, Tex., assignors to Standard Oil Development Company, a'corporation of Delaware Application July 13, 1945, Serial No. 604,832

6 Claims.

The present invention is directed to a method for treating a liquid fraction comprising a major portion of hydrocarbon and a minor portion of methyl chloride to remove at least the major portion of the methyl chloride from the hydrocarbon. The presentinvention is particularly directed to the treatment of mixtures of the type released in low temperature polymerization reactions used to produce rubber-like polymer and enables the valuable hydrocarbons present in these mixtures to be further processed and eliminates the rapid corrosion of equipment which has heretofore been encountered when treating such hydrocarbon materials The present invention may be descrfibed generally as involving the steps of bringing into intimate contact a feed stock comprising a major portion of hydrocarbons and a minor portion of methyl chloride with an alcohol having a substantial solubility in water to form an alcoholic solution of the feed stock. The alcoholic solution is then separated into a hydrocarbon fraction and an aqueous fraction by introducing water or an aqueous solution into the alcoholic solution, and gravity settling. The hydrocarbon fraction obtained is substantially free from methyl chloride and may be treated in additional steps, as for example distillation. thermal polymerization or dehydrogenation without causing the corrosion of equipment used for handling it which would result were not the methyl chloride previously removed from the hydrocarbon. The resultant aqueous phase may be further treated as desired to recover the alcohol and methyl chloride as such therefrom or to convert one or all of the constituents in' the aqueous phase into other constituents and recover them.

In the practice of the present invention, it will be found that a number of alcohols are suitable for contacting with the hydrocarbon feed stock; specific materials which may be mentioned by way of example are tertiary butyl alcohol, propyl alcohol, ethyl alcohol or methyl alcohol. Because of the relative ease in recovering the tertiary butyl alcohol from aqueous solutions by distillation it will often be advantageous to employ this material in preference to other alcohols having the requisite solubility characteristics. In treating the hydrocarbon feed stock, the Water soluble alcohol may be intimately contacted with the hydrocarbon feed stock to form a solution and water or an aqueous solution added to the alcoholic solution to cause a phase separation. Alternatively, a solution of alcohol in water may be intimately contacted with The present invention will now be described in greater detail in conjunction with the drawing in which- Fig. 1 is in the form of a diagrammatic flow sheet showing a polymerization process for producing a rubber-like polymer wherein a mixture of hydrocarbons and methyl chloride is obtained and wherein the mixture is treated to separate it into constituents, and

Fig. 2 is in the form of a diagrammatic fiow sheet showing a modification which may be substituted for an equivalent step in the process shown in Fig. l.

Turning now specifically to the drawing and first to Fig. l, a hydrocarbon feed stock including normal olefins, iso-olefin and diolefin is passed through line ll containing chiller l2 and discharged into reactor l3. The reactor i3 is shown symbolically as a rectangle and is provided with a partition indicated by dotted line H as indicating a separation into an upper reaction or mixing zone and a lower separating zone. A Friedel-Craft type catalyst dissolved in methyl chloride is passed through inlet line l5 and has mixed therewith additional methyl chloride through inlet H5. The mixture of Friedel- Crafts type catalyst and methyl chloride then passes through chiller I! and is discharged to the mixing zone of reactor i3. In reactor l3 the hydrocarbon feed stock reacts to form a rubberlike polymer; the rubber-like polymer is sepaof l 'riedel-Crafts type catalyst into the hydrocarbon stream to cause its admixture with the poly'-.

June 16, 1943, in the name or John D. Calfee,

Robert M. Thomas and Paul J. Flory and,'since this reaction as such does not form a part of 'the present invention, the reaction zone I! and its operation will not be described in any greater detail in the present application. I

The vaporous mixture withdrawn from reaction zone l3 through line is includes substantial amounts of normal olefins and iso -olefin and a minor amount of methyl chloride. This mixture is discharged through line is into an initial separating zone, such as a distillation column 20 provided with a heating coil 2|. Although distillation column 20 is shown as a single unit, it will be understood that'several distillation columns may be provided to accomplish the desired separation. In separating zone 20 the mixture ted thereto is separated into a low boiling methyl chloride fraction which may be removed as overhead through line 22 and one or more hydrocarbon fractions which are withdrawn through lines 23 and 26. A fraction, comprising predominantly iso-olefin contaminated with methyl chloride is withdrawn through line 23 and may be recycled to feed line ii. A hydrocarbon fraction comprising predominantly isoand normal oleflns and contaminated with a minor portion of methyl chloride is withdrawn as a bottoms stream through outlet 26.

In the drawing, line it conveys the hydrocarbon fraction contaminated with methyl chloride into a lower portion of column 25. Column 25 is arranged to allow the intimate contacting of the hydrocarbon material with a water soluble alcohol and with water to allow the separation of two liquid phases, a hydrocarbon liquid phase and an aqueous liquid phase. Accordingly, an alcohol having substantial solubility in water is charged into a mid-point of column 25 through inlet 26. The alcohol in liquid state and the hydrocarbon fraction in liquid state are intimately contacted and form an alcoholic solution. Water drocarbon stream passing through line It and is injected into an upper portion of the tower through inlet 21. The water flows downwardly in the tower and, upon com-mingling with the alcoholic solution, causes the formation of two phases, a hydrocarbon phase substantially free from methyl chloride and an aqueous phase including the water soluble alcohol and at least a major portion of the methyl chloride introduced into the tower through line 24. The aqueous phase is the heavier and flows downwardly in the tower while the hydrocarbon phase is the lighter and flows upwardly. The hydrocarbon phase comprises iso-olefins and normal oleflns and is removed from the top of the tower as a liquidfraction through outlet 28, The aqueous phase is removed from the lower end of tower 25 through outlet 29..

The process shown in Fig. 1 may be modified as illustrated in Fig. 2. It will be understood that Fig. 2 shows only a portion of the complete process and is intended to be substituted for corre- 4 than added directly to the tower. Aswiil be seen, the alcohol is added through line III to the hythe alcohol and hydrocarbon are thoroughly ad-' mixed by passing through mixing device ll which may, for example, be an orifice type incorporator and the mixture subsequently discharged into tower 25'. It will be understood that tower 25' operates in the same manner as tower 25 with the solution of hydrocarbon and alcohol brought into contact with water to cause a phase separation and wherein a hydrocarbon fraction 'is' removed through outlet 26" and an aqueous fraction is removed through outlet 29'. I

As an example illustrating the application 01' the present invention, the hydrocarbon feed-stock introduced by line H maybe a mixture of isobutylene, normal butylenes and a poly-olefin, such as butadiene, isoprene, piperylene and the like, and this feed stock may be chilled to a tem- Derature within the range of F. to -l00 F. The Friedel-Crafts type catalyst may be aluminum chloride dissolved in the methyl chloride and this catalyst solution may be similarly chilled to a low temperature and admixed with the chilled hydrocarbon feed stock in the reactor ll. In the reactor a, rubber-like polymer is produced and is withdrawn through outlet ll, while a mixture comprising isobutylene, normal butylenes, and methyl chloride is withdrawn through line l9. In the initial separating zone 20 the mixture is separated into a methyl chloride fraction and an isobutylene fraction while a mixture or isobutylene rich in normalbutylenes and contaminated with appreciable amounts of methyl chloride is withdrawn through line 24 and sent to vessel 25 where it is extracted to remove the methyl chloride from the hydrocarbons. The aqueous solution withdrawn from the bottom of the tower 25 comprises water, alcohol and methyl chloride. The hydrocarbon fraction withdrawn from the upper end of column 25 comprises isobutylene rich .in normal butylenes and free from methyl chloride and this fraction may be further treated in means not shown to utilize these valuable constituents without danger of corroding the equipment employed.

In order to illustrate further the practice ofthe'present invention, the following example is given.

Example Experiment No l 2 3 Charge:

Spent Butylene, cc. 1000 1W0 1000. Methyl Chloride, I

per cent 0.55 0.55 0.55. Treatment:

Extracted with 250 20% Alcohol m%Alcohol 1Y6 Alcohol cc.oi. in 2N in IN 11 IN NaOH NaOH NaOH. Extracted Butylene, 0. r 0.06.

per cent Methyl Chloride.

Experiment No 4 5 6 Charge:

Spent But lene,cc.. 1000. 1000 I000. Methyl hloride, 0.55 0.55 0.55. per cent. Treatment:

Extracted with 250 Z)%Alcohol 20%Alcohol 33% Alcohol cc. of. in water. in water. in water. Extracted Butylene, 0.12 0.16 0.02.

per cent Methyl Chloride. I

- 1 The alcohol used was tertiary butyl alcohol and each alcohol extraction was lollowed y three 250 cc. water washes.

It will be seen from the above table that the methyl chloride was removed from the hydrocarbon in amounts ranging from 71% to 95%.

While we have given specific examples illustrating the practice of the present invention, it is to be understood that such examples are for illustrative purposes only. It will be obvious to a worker skilled in the art that various modifications may be made in the practice described above without departing from the scope oi the invention.

Having fully described and illustrated the present invention, what we desire to claim is:

1. A method for treating a hydrocarbon mixture comprising'a major portion of butylene and having dissolved therein appreciable amounts of methyl chloride including the steps of intimately contacting said mixture in a liquid state with an alcohol having substantial solubility in water to form a solution in said alcohol, intimately contacting the alcoholic solution with water in suflicient amount to cause a separation of a hydrocarbon phase and an aqueous phase, and separately removing said phases.

2. A method for treating a feed stock comprising a major portion of butylenes and an appreciable amount of methyl chloride including the steps of bringing the feed stock in a liquid state into intimate contact with a water soluble alcohol to form a solution, intimately contacting said solution with an aqueous solution of sodium hydroxide and forming an aqueous phase including at least the major portion of the methyl chloride originally present in the feed stock and a hydrocarbon phase and separately.

removing said phases.

3. A method for treating a feed stock comprising methyl chloride in an amount of the order of 0.5% and a major portion of butylene including the steps of contacting the feed stock in a liquid state with an alcohol having substantial water solubility .to form an alcoholic solution. contacting the solution with water and forming a. butylene phase including no more than a 5 separately removing said phases.

4. A method in accordance with claim 3 in which the alcohol istertiary butyl alcohol.

5. A method of treating a feed stock comprising methyl chloride in an amount of the order of 0.5% and a major portion of butylenes including the steps of intimately contacting the feed stock in a liquid state with an alcohol having substantial water solubility to form a solution, intimately contacting said solution with an aqueous solution of sodium hydroxide to form an aqueous phase including at least a major portion of methyl chloride initially present in the feed stock and a butylenes phase including no more than a minor portion of the methyl chloride initially present in the ieed stock and separately removing said phases.

6. A method in accordance with claim 5 in which the alcohol is tertiary butyl alcohol.

OLIVER H. DAWSON.

HAMPTON G. CORNEEL.

REFERENCES CITED The following references are of record in the flie of this patent:

OTHER REFERENCES Jones et al., Chlorination of Natural Gas, Tech.

Paper 255, Dept. oi. the Interior, Bureau of Mines,

Pages -38 (1921).

Handbook of Chemistry and. Physics, 26th ed.,

Pub. by Chem. Rubber Pub. 00., Cleveland, Ohio,

pages 880-881, 8'72, 873, 660, 661, 665, 664 (1942). Allison et al., Jour. Ind. Eng. Chem., vol. 11, 943-8 (1919). 

